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Infectious Disease > Week 5: Parasitology Part II > Flashcards

Week 5: Parasitology Part II Flashcards

1
Q

learning objectives

A

For the parasitic organisms identify

  • the geographical region of risk
  • mode of transmission
  • Life-cycle
  • clinical symptoms
  • clinical complications of infection
  • laboratory diagnostic tests
  • appropriate treatment
  • side effects of treatment
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2
Q

Case 1

A
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3
Q

Question

A

D. Schistosoma japonicum

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4
Q

Schistosomiasis Life-cycle

A
  • Infected person (Reservoir) releases trematode eggs in urine or stool
  • Eggs contaminate freshwater
  • Eggs hatch and infect snails (intermediate host) and divide
  • Free swimming cercariae released into the water and penetrate human skin

People defecate oocytes which enter freshwater and eggs hatch and infect snails and divide, the snails release free-swimming cercariae into the water which penetrate human skin

Cercariae lose tails during penetration and become schistosomulae and enter the circulation and migrate to the portal blood in liver and mature into adult worms that perform sexual reproduction

Paired adult worms migrate to mesenteric venules of bowel/rectum laying eggs that circulate to the liver and are shed in stools to infect more snails

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5
Q

Schistosomiasis pathophysiology

A

eggs can migrate to the liver to be shed in stools or to other tissues such as wall of intestine or liver (mansoni or japonicum), bladder wall (haematobium) -> granulomas -> fibrosis

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6
Q

Liver Schistosomiasis

A
  • Schistosoma mansoni
  • Schistosoma japonicum
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7
Q

Bladder wall fibrosis Schistosomiasis

A

Schistosoma haematobium

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8
Q

Clinical manifestations of Schistosomiasis

A
  • Swimmer’s itch: Cercariae penetrating skin (pruritic papular rash after penetration)
  • Katayama fever (Acute schistosomiasis)
    • systemic hypersensitivity reaction to Schistosoma antigens occurring 1-2 months post-exposure
    • Fever, chills, cough, urticaria, angioedema, arthralgias, dry cough, abdominal pain, lymphadenopathy, and splenomegaly
    • Massive eosinophilia
  • Deposited eggs cause granulomas & fibrosis
    • periportal fibrosis/portal hypertension
    • Hematuria and bladder cancer
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9
Q

Would you predict that a patient with Schistosomiasis would have eosinophilia?

A

Yes, during swimmer’s itch phase and especially during the Katayama fever.

The granulomatous stage doesn’t have a big immune response

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10
Q

What laboratory test to diagnose Schistosomiasis

A
  • Stool test if it is in the liver and biliary system
  • Urine for bladder
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11
Q

Schistosoma species

A
  • Schistosoma mansoni
  • Schistosoma haematobium
  • Schistosoma japonicum
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12
Q

Schistosoma mansoni region

A
  • Africa
  • South America
  • Carribean
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13
Q

Schistosoma mansoni eggs found in

A
  • Stool
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14
Q

Schistosoma haematobium region

A
  • Africa
  • Middle East
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15
Q

Schistosoma haematobium eggs found in

A

Urine

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16
Q

Schistosoma micro egg exam

A
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17
Q

Schistosoma mansoni micro egg exam

A
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18
Q

Schistosoma japonicum region

A
  • Indonesia
  • China
  • SE Asia
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19
Q

Schistosoma japonicum eggs found in

A

Stool

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20
Q

Schistosoma japonicum micro exam of eggs

A
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21
Q

Schistosomiasis treatment

A

Praziquantel

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22
Q

Praziquantel MOA

A

Kills adult schistosomes and causes them to become dislodged from mesenteric, hepatic or pelvic veins -> phagocytosed in liver

Kills adult worms (does not kill eggs or treat fibrosis)

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23
Q
A
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24
Q

Praziquantel best used when?

A

During acute schistosomiasis (single dose 6-8 weeks after last exposure to potentially contaminated freshwater)

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25
Praziquantel side effects
Majority of side effects develop due to host immune reaction to killed parasites (release lots of antigens when they die)
26
Examples of Trematode infections
* Schistosomiasis * Paragonimus westernmani * Clonorchis sinensis * Fasciola hepatica
27
Paragonimus westernmani region
SE Asia
28
Paragonimus westernmani AKA
Lung fluke
29
Paragonimus westernmani transmission
ingestion of undercooked crabs/crayfish contaminated with metacercariae
30
Signs & symptoms of Paragonimus westernmani
* Lung cyst rupture * Chronic bronchitis * TB-like picture
31
Paragonimus westernmani diagnosis
* eggs in sputum * serology
32
Paragonimus westernmani Tx
Praziquantel
33
Clonorchis sinensis region
Asia
34
Clonorchis sinensis AKA
Liver fluke
35
Clonorchis sinensis transmission
ingestion of undercooked freshwater fish contaminated with metacercariae
36
Signs & Symptoms of Clonorchis sinensis
* obstructive jaundice * biliary strictures * pigmented gallstones * cholangitis * cholangiocarcinoma
37
Clonorchis sinensis Dx
Eggs in stool
38
Clonorchis sinensis Tx
Praziquantel
39
Would becoming a vegetarian eliminate the risk of intestinal parasite infection?
No, for example Fasciola hepatica
40
Biliary strictures & cholagniocarcinoma and Hx of undercooked fish
Clonorchis sinensis
41
Undercooked crab/crayfish
Clonorchis westernmani
42
Fasciola hepatica region
Worldwide trematode
43
Fasciola hepatica AKA
Common Liver Fluke
44
Common Liver Fluke
Fasciola hepatica
45
Fasciola hepatica definitive host
Sheep/cattle
46
Fasciola hepatica intermediate host
Snail
47
Fasciola hepatica Incidental host
Human
48
Fasciola hepatica transmission
ingestion of raw watercress or other plants contaminated with metacercariae -\> migrate through duodenal wall -\> peritoneum -\> liver -\> biliary ducts -\> obstruction
49
Fasciola hepatica Dx
Eggs in stool or duodenal or biliary aspirated
50
Fasciola hepatica Tx
Triclabendazole
51
Triclabendazole caveat
Not FDA approved so must obtain from CDC
52
Case 2
53
Question
C. Taenia solium
54
Taenia solium type
Helminth: Cestode/tapeworm
55
Taenia solium Intermediate host
pig
56
Taenia solium definitive host
human
57
Taenia solium transmission
* Human ingestion of larval cyst in undercooked pork causes **Taeniasis** (intestinal infection) with adult worms -\> excrete eggs in stool * Human ingestion of eggs from fecal-contaminated water or vegetation causes **Cysticercosis** (tissue infection)
58
Human ingestion of larval cyst of Taenia solium
Taeniasis (tape-worm intestinal infection)
59
Human ingestion of larval cyst of Taenia solium
Cysticercosis (tissue infection)
60
Describe the life cycle of Taenia solium
* pigs ingest fecal-contaminated feed * oncospheres hatch and penetrate pig intestinal wall and circulate to the musculature * Oncospheres develop into cysticerci in pig muscle * Humans infected by ingesting undercooked or raw infected meat * Taeniasis: Scolex attaches to intestines and grows to adults in small intestine * Cysticercosis: oncospheres hatch penetrate the intestinal wall and circulate to musculature, cysticerci may develop in any organ being more common in subcutaneous tissues as well as in the brain and eyes
61
Tenia solium Dx
* Imaging * serology
62
Tenia solium Tx
Praziquantel x 1 (cysticidal) Albendazole (cysticercosis) or may not need treatment
63
Diphyllobathrium latum AKA
Fish tapeworm
64
Diphyllobathrium latum transmission
Ingestion of undercooked freshwater fish
65
Diphyllobathrium latum signs & symptoms
competes for vit B12 in host intestine -\> macrocytic anemia
66
Diphyllobathrium latum Dx
eggs in stool
67
Diphyllobathrium latum Tx
Praziquantel
68
An infection with which cestode can lead to hydatid cyst in the liver or lung?
Echinococcus
69
How does a patient become infected with Echinococcus?
70
How is Echinococcus Dx'ed?
* Imaging to see hydatid cyst * Serologies * Never aspirate hydatid cyst because can cause anaphylactic shock
71
Who commonly gets Echinococcus?
Raw food or food infected with dog feces (Sheep herders commonly get Echinococcus)
72
Case 3
73
Do you aspirate hydatid cyst?
No, can cause anaphylactic shock
74
Question
C. Stool Ova & Parasite
75
Case 3 Stool sample
Strongyloidiasis
76
Question
C. Strongyloides stercoralis
77
Strongyloides stercoralis stool and blood agar
78
Describe the life-cycle of Strongyloides stercoralis
* Rhabdiform larvae in the intesine are excreted in stool and * autoinfect * but also develop into free-living adult worms that perform sexual reproduction * eggs are produced by fertilized female worms * Rhabditiform larvae hatch from embryonated eggs * The rhabditiform larvae develop into infective filariform * Infective filariform larvae penetrate the intact skin initiating the infection * The filariform larvae enter the circulatory system and are transported to the lungs and penetrate the alveolar spaces, they are carried to the trachea and pharynx, swallowed and reach the small intestine where they become adults * Autoinfection rhabditiform larvae in large intestine become filariform larvae, penetrate intestinal mucosa or perianal skin and follow the normal infective cycle * Eggs deposited in the intestinal mucosa hatch and migrate to the lumen * Rhabditiform larvae in the intestine are excreted in stool
79
Describe the initial infection of Strongyloidiasis
Filariform larvae penetrate the skin -\> migrate through tissue into blood -\> to lungs -\> into alveoli -\> trachea -\> cough up and swallow -\> in intestine -\> can cross intestine wall (perforation) to peritoneum
80
Strongyloidiasis signs & symptoms of initial infection
**Skin** * Intense pruritis at site of skin penetration **Lungs** * Transient fever, cough and wheezing **GI** * symptoms only if lots of worms * abdominal pain, vomiting, diarrhea * Perforation with peritonitis from GI flora
81
Strongyloidiasis signs & symptoms of autoinfection
* Larva currens: peri-anal serpiginous urticarial rash * can lead to chronic infection for decades * Hyperinfection syndrome: Autoinfection in immunocompromised patients, Abdominal pain, diffuse pulmonary infiltrates, septicemia or meningitis with GNR
82
Describe autoinfection of Strongyloidiasis
female worm lays eggs in human bowel wall -\> larva hatch -\> larval invasion of perianal skin
83
Strongyloidiasis stercoralis Dx
Stool & blood agar In the stool: Rhabditiform larvae in stool, sputum, CSF, other body fluid Stool culture shows GNR along the track of movement of larvae
84
Strongyloidiasis Tx
* Ivermectin x 1 * Second line: Albendazole x 7 days
85
Ascaris lumbricoides type
Nematode/round-worm
86
Ascaris lumbricoides transmission
Fecal-oral
87
Ascaris lumbricoides infection type
Intestinal infection
88
Ascaris lumbricoides Dx
Eggs in stool
89
Ascaris lumbricoides Tx
* Albendazole * Mebendazole
90
Ascaris lumbricoides overview
91
Describe the life-cycle of Ascaris lumbricoides
* Ingestion of eggs in fecal-contaminated food * egg releases larval worm which penetrates duodenum * Carried in bloodstream to pulmonary circulation * Larvae break free in alveoli where they mature over 3 weeks * Coughed up and swallowed * Adults mature in intestine & copulate and release eggs in stool
92
Necator americans region
New world
93
Ancylostoma duodenale region
Old world
94
Necator americans description
Roundworm "hookworm"
95
Necator americans distribution
Tropics, subtropics
96
Necator americans Transmission
Contaminated soil -\> larvae penetrate through skin
97
Necator americans definitive host
humans
98
Necator americans clinical syndrome
* cutaneous larva migrans & eosinophilia: Pruritic maculopapular rash at site of penetration * Nausea, vomiting, diarrhea, abdominal pain * Anemia: sucks blood from intestinal wall
99
Necator americans Dx
Detection of eggs in stool
100
Necator americans Tx
Albendazole
101
Describe the life cycle of Necator americans
* eggs in feces, rhabditiform larva hatches * larva in fecal-contaminated soil in the tropics/subtropics become filariform larva * filariform larva penetrate the skin from walking barefoot and migrates through blood vessels to lungs * larva penetrate alveoli and ascend to pharynx and are swallowed (transient pulmonary symptoms) * become adult worms in intestines and perform sexual reproduction and cause anemia in host * Are released in feces
102
Necator americanus analogous in old world
Ancylostoma duodenale
103
Trichuris trichuria type
Nematode
104
Trichuris trichuria exposure
soil containing eggs
105
Trichuris trichuria clinical syndrome
whipworm: tenesmus, rectal prolapse
106
Trichinella type
Nematode
107
Trichinella exposure
Ingesting contaminated food (pig, bear)
108
Trichinella clinical syndrome
* mild diarrhea * periorbital edema * myalgias
109
Dracunculus mediensis description
nematode
110
Dracunculus mediensis exposure
ingestion of contaminated water
111
Dracunculus mediensis clinical syndrome
Guinea worm: malaise, fever, adult worm emerges
112
Dracunculus mediensis type
Nematode
113
Enterobius vermicularis type
nematode
114
Enterobius vermicularis exposure
Fecal-oral
115
Enterobius vermicularis clinical syndrome
* intestinal pinworm * anal pruritis
116
Loa Loa type
Nematode
117
Loa Loa exposure
* Deer fly * Horse fly
118
Loa Loa Clinical syndrome
* Conjunctival worm
119
Onchocerca volvulus type
Nematode
120
Onchocerca volvulus exposure
Female blackfly bite
121
Onchocerca volvulus clinical syndrome
River blindness
122
Toxocara canis type
nematode
123
Toxocara canis exposure
fecal-oral
124
Toxocara canis clinical syndrome
visceral larva migrans
125
Wuchereria bancrofti type
nematode
126
Wuchereria bancrofti exposure
female mosquito
127
Wuchereria bancrofti clinical syndrome
Elephantiasis (lymphatic filariasis)

Infectious Disease (82 decks)

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